When I was leveling my alt, I accepted a Quest named "The Kessel Run" it´s the one where you get the elekk mount at lvl 10 to warn some people near exodar. This quest can be found at bloodmyst isle.
You have 15 min for this quest, what happened is that I warned the 3 people, got about 1.3k exp total. And then went away from keyboard, and the quest failed. Then went back, did it again, and again I got exp for it.
I just repeated this 'till I got level 15 from level 10. Boring, but quick exp